Attempting to desalinate seawater

[justbob54]

I'm justbob54 My pupose of being here is learn how to turn saltwater into fresh water I have built a grude still by pure luck my first brew came out pure enough that it would not boil again. I started with tapwater and made distilled water. I haven't read much, but I have began to find errors in my ways already leading me to the changes I need to make to improve.

[contrahead]

... My pupose of being here is learn how to turn saltwater into fresh water...

If your main concern is the desalination of seawater for drinking then you should study solar distillation / not liquor distillation. Yes, the methods we use to make liquor can also be applied to making fresh water; but would be very inefficient. The fossil fuels or electricity we use are expensive, as are the copper and stainless steel equipment.

There have been some large, experimental, publicly funded desalination plants built in the last decade that employ reverse osmosis desalination. But these plants also will be prohibitively expensive to operate and to replicate in the long run.

About a century and a half ago, in the driest desert in the world (the Atacama Desert in 1872), the first useful solar still for desalination was designed and built by a Swedish engineer named Charles Wilson. Wilson built a series of stills for a saltpeter mining company (in Las Salinas, Chile) that together were capable of purifying 23,000 liters of clean water per day. (From brackish water, probably pumped from shallow wells).

Mabey check out this thread:
viewtopic.php?f=1&t=77009&p=7589140&hil ... l#p7589140

[driscolldb]

I'm in the same boat you are, as far as seawater desalination (and swamp water purification), and came here for some cooling idea. The other poster said look into solar issues but that only works when the sun shines, isn't practical for very large amounts of water in a shorter time, making fresh drinking water in winter environments, and doesn't address the issue of needing to use some kind of fuel. Solar stills are great but if you need water for a family each and every single day of the year you won't be doing that with a solar still.

My intent is produce 5 gallons of fresh water a day in the simplest manner possible. Cooling the vapor is my main concern as I won't have water to run through the system and preferably don't want to force air through it either. It takes a lot more copper to cool water vapor over alcohol and again a lot more to air cool it. So I started researching air cooled stills and started asking exactly how much 4" copper pipe would I need to run the vapor through.

Of course this all depends on how much water you want and how fast you want it. Turning down the heat a bit will slow the process down and will require a lot less pipe.

I came to this forum know that some people have a lot more knowledge on turning vapor into liquid and doing it in a compact manner. I've found some very useful info, especially the air-cooled builds.

My initial experiments with this are just tests. Once I find out the amount of copper I need I can refine it. As it is now none of the pipe has to be cut up or bent and can be used for other things if necessary or this setup can be made from existing pipe easily.

I'm using a 5 gallon pressure canner that I cannot chop up for this only so it is unmodified and has a hose from the pressure vent into the copper pipe. I need to be able to do 5 gallons finished product in one run if possibly so this means more than one pot, a bigger one, or back to back runs.

I started with 1" copper pipe, no soldering, no bending. 10 feet in a straight line wasn't near good enough. 5 feet of 1 inch pipe surrounded in a bunch by five other pipes of equal size (as nothing but heat sinks) will do the trick if I reduced stove heat to half, but only produces under a quart an hour.

I can max out the oven heat if I forced air through the heat sink pipes (this is undesirable) with a fan just to get an idea. The end where I get water is only slight warm to the touch when I do this.

My next steps:

Separate all the pipe and spread the vapor out through all six of them and see if the system performs

I have some 4 inch pipe on order and will test a 5 foot section of that then test is again with 6 inch heat sink pipes.

As I said before this is very experimental in finding out just how much copper I need to have a very simple static no forced air, no water circulation condenser that doesn't require modifying any of the copper.

Let me know if youre interested in my progress. In the very least I think this will add to the air-cooled debates

[habaz]

I'm in the same boat you are, as far as seawater desalination (and swamp water purification), and came here for some cooling idea. The other poster said look into solar issues but that only works when the sun shines, isn't practical for very large amounts of water in a shorter time, making fresh drinking water in winter environments, and doesn't address the issue of needing to use some kind of fuel. Solar stills are great but if you need water for a family each and every single day of the year you won't be doing that with a solar still.

My intent is produce 5 gallons of fresh water a day in the simplest manner possible. Cooling the vapor is my main concern as I won't have water to run through the system and preferably don't want to force air through it either. It takes a lot more copper to cool water vapor over alcohol and again a lot more to air cool it. So I started researching air cooled stills and started asking exactly how much 4" copper pipe would I need to run the vapor through.

Of course this all depends on how much water you want and how fast you want it. Turning down the heat a bit will slow the process down and will require a lot less pipe.

I came to this forum know that some people have a lot more knowledge on turning vapor into liquid and doing it in a compact manner. I've found some very useful info, especially the air-cooled builds.

My initial experiments with this are just tests. Once I find out the amount of copper I need I can refine it. As it is now none of the pipe has to be cut up or bent and can be used for other things if necessary or this setup can be made from existing pipe easily.

I'm using a 5 gallon pressure canner that I cannot chop up for this only so it is unmodified and has a hose from the pressure vent into the copper pipe. I need to be able to do 5 gallons finished product in one run if possibly so this means more than one pot, a bigger one, or back to back runs.

I started with 1" copper pipe, no soldering, no bending. 10 feet in a straight line wasn't near good enough. 5 feet of 1 inch pipe surrounded in a bunch by five other pipes of equal size (as nothing but heat sinks) will do the trick if I reduced stove heat to half, but only produces under a quart an hour.

I can max out the oven heat if I forced air through the heat sink pipes (this is undesirable) with a fan just to get an idea. The end where I get water is only slight warm to the touch when I do this.

My next steps:

Separate all the pipe and spread the vapor out through all six of them and see if the system performs

I have some 4 inch pipe on order and will test a 5 foot section of that then test is again with 6 inch heat sink pipes.

As I said before this is very experimental in finding out just how much copper I need to have a very simple static no forced air, no water circulation condenser that doesn't require modifying any of the copper.

Let me know if youre interested in my progress. In the very least I think this will add to the air-cooled debates

Why dont you use the sea water to cool your condenser?

[driscolldb]

"Why dont you use the sea water to cool your condenser? "

Because the system is designed for not only sea water but water of any kind, too. I may have to collect water from multiple sources and won't have more to cool it with. As I said I wanted a simple system that didn't take any modification so I could build it out of nothing but copper pipe. It is a pot still of the simplest design that will take nothing other than simply running vapor through the copper pipe. An indoor system with no pump, no pouring and no large containers of liquid to run copper through. I'm not next to the sea, or any other large bodies of water. If I have to travel to collect water I don't want to have to carry or bring even more of it to keep it on hand. I fully understand the power of water cooling, my intent is to design a system that does not require it.

[habaz]

I thought you were doing something for your boat. Misunderstanding

[driscolldb]

"I thought you were doing something for your boat. Misunderstanding "

No worries

[Yummyrum]

Hee hee , if you want to distill sea and swamp water thats fine ….. but you’re amongst friends here … you can admit to distilling fermented things too if you want